US010132144B2 (12 ) United States Patent ( 10) Patent No. : US 10 , 132 , 144 B2 Lawson et al. ( 45 ) Date of Patent : Nov . 20 , 2018 ( 54 ) GEOCHEMICAL METHODS FOR ( 58 ) Field of Classification Search MONITORING AND EVALUATING CPC .. CO9K 8 / 58 ; CO9K 8 /582 ; CO9K 8 / 90 ; E21B MICROBIAL ENHANCED RECOVERY 43 / 16 OPERATIONS See application file for complete search history. (71 ) Applicants :Michael Lawson , Spring , TX (US ); Amelia C . Robinson , Houston , TX (56 ) References Cited (US ) ; Daniel A . Stolper , Berkeley , CA U . S . PATENT DOCUMENTS (US ) 4 , 833 , 915 A 5 / 1989 Radd et al . (72 ) Inventors : Michael Lawson , Spring , TX (US ); 4 ,905 ,761 A 3/ 1990 Bryant Amelia C . Robinson , Houston , TX ( Continued ) (US ) ; Daniel A . Stolper, Berkeley, CA (US ) FOREIGN PATENT DOCUMENTS CN 102154453 A 8/ 2011 (73 ) Assignee : ExxonMobil Upstream Research WO WO 2002 /059351 A2 8 / 2002 Company , Spring , TX (US ) ( Continued ) ( * ) Notice : Subject to any disclaimer, the term of this patent is extended or adjusted under 35 OTHER PUBLICATIONS U .S . C . 154 (b ) by 0 days. Chung et al. ( 1988) " Origin of gaseous hydrocarbons in subsurface (21 ) Appl . No. : 15 /668 , 395 environments : theoretical considerations of carbon isotope distri bution ” , Chemical Geology, vol. 71 , pp . 97 - 103 . (22 ) Filed : Aug. 3 , 2017 (Continued ) (65 ) Prior Publication Data Primary Examiner — Zakiya W Bates US 2018 /0066504 A1 Mar . 8 , 2018 Assistant Examiner — Crystal J Miller (74 ) Attorney, Agent, or Firm — Exxonmobil Upstream Related U . S . Application Data Research Company Law Department ( 60 ) Provisional application No . 62 /382 , 921 , filed on Sep . 2 , 2016 . (57 ) ABSTRACT Described herein are methods and techniques that utilize ( 51 ) Int. Ci. molecular geochemistry and isotopic signatures to monitor E21B 43 / 16 ( 2006 . 01 ) microbial enhanced gas and oil recovery operations. The CO9K 8 /582 ( 2006 .01 ) methods and techniques utilize multiply substituted isoto (Continued ) pologue signatures, clumped isotope signatures , and /or posi (52 ) U . S . CI. tion - specific isotope signatures of one or more byproducts of CPC ...... E21B 43 / 16 ( 2013 .01 ) ; C09K 8 /582 the microbial stimulation techniques to determine the effec (2013 .01 ) ; C09K 8 /90 (2013 . 01 ); E21B 43/ 25 tiveness of a microbial stimulation technique . ( 2013 .01 ) ; (Continued ) 18 Claims, 2 Drawing Sheets

Collect sample from producing weil to characterizeisotopic the natural signature background

Slimulate the well using microbial stimulation techniques

Collect sample turn the stimulated well to characterize the induced isotopic signature 108 Analyze the clifferences between the induced isotopic signature and the background isotopic signature 110 Optionally , collcct samples for the Stimulated well over a period of time to characterize the induced isotopic www. signanire over time . 112 Optionally , analyze the differences in the induced isotopic signature over tinc 114 Develop or refine stimulation strategy trased on the inducecl isotopic signalLiTV - 116 Produce hydrocarbons US 10 ,132 ,144 B2 Page 2

(51 ) Int . CI. 2015 / 0240633 A1 * 8 / 2015 Akkurt ...... E21B 49 /088 CO9K 8 / 90 175/ 50 ( 2006 .01 ) 2015 /0284810 Al 10 /2015 Knight et al . E21B 43 / 25 ( 2006 .01 ) 2015 /0291992 Al 10 /2015 Al-Moniee et al . GOIN 33 / 28 ( 2006 .01 ) 2016 / 0018558 A1 * 1 / 2016 Bond GOIV 8 / 02 GOIV 9 /00 ( 2006 . 01) 250 / 255 C12P 1 /00 2016 / 0084045 Al 3 / 2016 Lawson et al. ( 2006 .01 ) 2016 /0084080 A1 3 / 2016 Lawson et al. C12P 39 / 00 (2006 .01 ) 2016 / 0084081 Al 3 / 2016 Lawson et al. U .S . Ci. 2016 / 0084817 A1 3 / 2016 Lawson et al. 2016 /0222781 A18 / 2016 Lawson et al . CPC ...... GOIN 33 /2823 (2013 . 01 ) ; GOIV 9 /007 2016 /0222782 A1 * 8 /2016 Lawson ...... GOIN 33 / 241 (2013 . 01 ) ; C12P 1/ 00 ( 2013 .01 ); C12P 39 /00 2016 / 0258922 A1 * 9 / 2016 Formolo ...... E21B 49 / 00 (2013 .01 ) 2016 /0272962 AL 9 /2016 Kohr 2016 /0341038 A1 * 11/ 2016 AbuAli ...... GOIN 1 / 2294 ( 56 ) References Cited U . S . 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Province , Porcupine Basin , Offshore Ireland ( IODP Expedition 7 , 809 ,538 B2 10 / 2010 Thomas 307 ) ” , Marine Geology , vol . 282 , pp . 91 - 101. 8 ,071 , 295 B2 12 / 2011 Ashby Ozgul ( 2002 ) , “ Geochemical Assessment of Gaseous Hydrocar 8 ,316 ,933 B2 11/ 2012 Kohr bons : Mixing of Bacterial and Thermogenic Methane in the Deep 8 ,316 , 934 B2 11/ 2012 Pietrobon Subsurface Petroleum System , Gulf of Mexico Continental Slope ” , 8 , 355 , 872 B2 1/ 2013 Rowan Thesis in partial fulfillment of the requirements for the degree of 8 , 476 ,016 B2 7 / 2013 Ashby Master of Science at Texas A & M University , pp . 1 -167 . 8 , 505 , 375 B2 8 / 2013 Smalley Prinzhofer et al. (2003 ), “ Gas Isotopes Tracing : An Important Tool RE44 ,728 E 1 / 2014 Pope et al. for Hydrocarbons Exploration " , Oil & Gas Science and Technology , 8 ,695 , 703 B2 4 / 2014 Dinariev et al. Rev . Ifp ., vol. 58 , No . 2 , pp . 299 - 311 . 8 , 714 , 246 B2 5 / 2014 Pop et al. Berner, U . et al. , “ Maturity Related Mixing Model for Methane , 8 , 760 ,657 B2 6 / 2014 Pope et al . Ethane and Propane , Based on Carbon Isotopes, ” Advances in 8 , 950 , 251 B2 2 / 2015 Valentine Organic Geochemistry 13 ( 1 - 3 ) , ( 1987 ) , pp . 67 - 72 . 9 .068 , 107 B2 * 6 / 2015 Larter C09K 8 /582 9 , 146 , 225 B2 9 / 2015 Pottorf et al. Bigeleisen , J. et al. , “ Calculation of Equilibrium Constants for 9 ,594 ,879 B2 3 / 2017 Eiler Isotopic Exchange Reactions, " J . of Chemical Physics , 15 ( 5 ) , (May 9 ,612 ,231 B2 4 / 2017 Pottorf et al . 1947 ), pp . 261- 267. 9 ,670 ,395 B2 6 / 2017 McDaniel Bloino , J. et al. , “ General Perturbative Approach for Spectroscopy , 2006 /0154306 A1 7 / 2006 Kotlar et al . Thermodynamics and Kinetics : Methodological Background and 2007 /0251146 A1 * 11/ 2007 Larter ...... CO9K 8 / 582 Benchmark Studies, ” J. of Chemical Theory and Computation 8 , 48 / 127 . 5 ( 2012 ), pp . 1015 - 1036 . 2008/ 0040086 A1 2 / 2008 Betancourt et al . Burnham , A . K . et al. , " A Chemical Kinetic Model of Vitrinite 2008/ 0147326 A1 6 / 2008 Ellis Maturation and Reflectance ,” Geochimica et Cosmochimica Acta 2009 / 0071239 A 3 / 2009 Rojas et al. 53 , ( 1989 ) , pp . 2649 - 2657 . 2010 /0015612 Al 1 / 2010 Pelham et al. 2010 / 0086180 A1 4 /2010 Wallace Bryant , R . S . et al ., “ Review of Microbial Technology for Improving 2010 / 0257004 Al 10 / 2010 Perlmutter et al . Oil Recovery ," SPE Reservoir Engineering 4, (1989 ), pp . 151- 154 . 2010 /0279290 AL 11/ 2010 Sleat et al. Chung , H . M ., et al. , “ Use of Stable Carbon Isotope Compositions of 2011 / 0250582 Al 10 / 2011 Gates et al. Pyrolytically Derived Methane as Maturity Indices for Carbona 2011/ 0308790 Al 12 / 2011 Strapoc et al . ceous Materials ,” Geochimica et Cosmochimica Actam 43 , ( 1979 ) , 2012 /0134749 AL 5 / 2012 Darrah pp . 1979 -1988 . 2012 / 0158306 A16 / 2012 Busche et al. 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References Cited Stolper, D . A . et al ., “ Distinguishing and Understanding Thermogenic ( 56 ) and Biogenic Sources of Methane Using Multiply Substituted OTHER PUBLICATIONS Isotopologues, " Geochimica et Cosmochimica Acta 161, ( 2015 ) , pp . 219 - 247 . Liu , Q . et al. , “ On the Proper Use of the Bigeleisen -Mayer Equation Stolper, D . A . et al. , “ Combined C - D and D -D Clumping in Meth and Corrections to it in the Calculation of Isotopic Fractionation ane: Methods and Preliminary Results ,” Geochimica et Cosmochimica Acta 126 , ( 2014 ), pp . 169 - 191 . Equilibrium Constants ,” Geochimica et Cosmochimica Acta 74 , Torgersen , T. et al. , “ Air -Xe Enrichments in Elk Hills Oil Field ( 2010 ) , pp . 6965- 6983 . Gases : Role of Water in Migration and Storage ,” Earth and Plan Reeves, E . P . et al. , “ Hydrogen Isotope Exchange Between n - Al etary Science Letters 167 , ( 1999 ) , 239 - 253 . kanes and Water Under Hydrothermal Conditions, ” Geochimica et Truhlar, D . G . et al. , “ Simple Perturbation Theory Estimates of Cosmochimica Acta 77 , ( 2012 ) , pp . 582 - 599 . Equilibrium Constants from Force Fields, " J . Chem . Phys 94 ( 1 ) , Richet, P . et al ., " A Review of Hydrogen , Carbon , Nitrogen , ( Jan . 1 , 1991 ) , pp . 357 - 359 . Oxygen , Sulphur, and Chlorine Stable Isotope Fractionation Among Urey , H . C . et al. , “ Some Thermodynamic Properites of the H ' H ” , Gaseous Molecules, ” Ann . Rev . Earth Planet. Sci . 5 , ( 1977 ) , pp . H 'H _Molecules and Compounds Containing the H? Atom ,” J. of 65 - 110 . Chemical Physics 1 , ( Feb . 1933 ) , pp . 137 - 143 . Rustad , J . R . et al ., “ Calculation of Boron - Isotope Fractionation Van Hamme, J. D . et al ., “ Recent Advances in Petroleum Microbi Between B (OH ) ( aq ) and BG (OH ) 2 - (aq ), ” Geochimica et ology, ” Microbiology and Molecular Biolology Review , (Dec . 2003 ) , Cosmochimica Acta 74 , (2010 ), pp . 2843 - 2850 . pp . 503 - 549 . Sandrea , I. et al ., “ Global Oil Reserves — Recovery Factors Leave Vidler , M . et al. , " Accurate Partition Function and Thermodynamic Vast Target for EOR Technologies, ” Oil & Gas Journal 105 , (Nov . Data for Water, ” J . of Chemical Physics 113 ( 21) , (Dec . 1 , 2000 ), pp . 5 , 2007 ), pp . 1- 8 . 9766 - 9771. Stahl, W . J . et al ., “ Carbon and Nitrogen Isotopes in Hydrocarbon Wang, D . T . et al. , “ Nonequilibrium Clumped Isotope Signals in Research and Exploration , ” Chemical Geology 20 , ( 1977 ) , pp . Microbial Methane ,” Science 348 , pp . 428 -431 . 121 - 149 . Wang, Y. et al. , “ Equilibrium ? H /' H Fractionations in Organic Stolper, D . A ., “ New Insights into the Formation and Modification Molecules : I . Experimental Calibration of AB Initio Calculations, " of Carbonate - Bearing Minerals and Methane -Gas in Geological Geochimica et Cosmochimica Acta 73 , (2009 ) , pp . 7060 - 7075 . Systems Using Multiply Substituted Isotopologues , ” Thesis, Cali Webb , M . A . et al ., “ Position - Specific and Clumped Stable Isotope fornia Institute of Technology, (2014 ), Pasadena , CA , pp . 1 - 160 . Studies : Comparison of the Urey and Path - Integral Approaches for Stolper, D . A . , “ New Insights into the Formation and Modification Carbon Dioxide, Nitrous Oxide, Methane, and Propane, ” J. of of Carbonate -Bearing Minerals and Methane -Gas in Geological Physical Chemistry 118 , ( 2014 ) , pp . 467 - 474 . Systems Using Multiply Substituted Isotopologues, ” Thesis , Cali Whiticar , M .J ., “ Stable Isotope Geochemistry of Coals, Humic fornia Institute of Technology , ( 2014 ) , Pasadena , CA , pp . 161- 305 . Kerogens and Related Natural Gases ,” Int' l. J . of Coal Geology 32 , Stolper, D . A . et al. , “ Formation Temperatures of Thermogenic and ( 1996 ) , pp . 191 - 215 . Biogenic Methane ,” Science 344 (6191 ) , ( Jun . 27 , 2014 ) , pp . 1500 1503 . * cited by examiner U. S . Patent atent NoNov . 20 , 2018 Sheet 1 of 2 US 10, 132 , 144 B2 102

Collect sample from producing well to characterize the natural background isotopic signature ...... - 104

Stimulate the well usingmicrobial stimulation techniques 106 Collect sample from the stimulated well to characterize the induced isotopic signature 108 Analyze the differences between the induced isotopic signature and the background isotopic signature 110 Optionally, collect samples form the Stimulated well over a period of time to characterize the induced isotopic signature over time

Optionally, analyze the differences in the induced isotopic signature over time 114 Develop or refine stimulation strategy based on the induced isotopic signature - 116

Produce hydrocarbons

FIGURE 1 atent Nov . 20 , 2018 Sheet 2 of 2 US 10 , 132 ,144 B2

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FIGURE 2

Rapid response

with diffusion 418.TC Sustained response

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MEOR treatment MEOR treatment

FIGURE 3 US 10 , 132 , 144 B2

GEOCHEMICAL METHODS FOR coalbed methane production to form microbial enhanced MONITORING AND EVALUATING coalbed methane ( “ MECOM ” ) and extend the production life MICROBIAL ENHANCED RECOVERY of these types of assets . OPERATIONS MEOR and MECOM techniques typically involve either 5 the external stimulation of in situ indigenous microbial CROSS -REFERENCE TO RELATED communities or the introduction of exogenous microbial APPLICATIONS communities ( e . g . , microbial populations that are introduced to the subsurface through water / fluid injection into the This application claims the benefit of U .S . Provisional subsurface ). The use ofmicrobial stimulation techniques can Patent Application No. 62/ 382 , 921 filed Sep . 2 , 2016 , the improve the properties of the crude oil in the formation ; disclosure of which is incorporated herein by reference. modify the wettability in the reservoir ( e . g . , the microor ganisms can mediate changes in the wettability of oil FIELD OF THE INVENTION droplets by growing on the droplet and changing the surface 15 of the oil to a less hydrophobic surface ) ; generate biosur Described herein are geochemical methods for monitor factants that can reduce interfacial tension ; make the hydro ing and evaluating microbial enhanced recovery operations. carbons more mobile in the subsurface (e . g ., the microor In particular , described herein are methods for utilizing ganisms can produce lower molecular weight hydrocarbons isotopic signatures, such as multiply substituted isotopo by enzymatically cleaving larger hydrocarbons into smaller logue signatures , clumped isotope signatures, and /or posi - 20 molecules, thereby reducing the crude oil 's viscosity ); alter tion - specific isotope signatures , to monitor and evaluate the permeability of the formation ( e . g . , the microorganisms microbial enhanced gas and oil recovery operations. can produce low molecular weight organic acids from the biodegradation of hydrocarbons which can cause rock dis BACKGROUND solution ) ; increase formation pressure ( e. g ., the microorgan 25 isms can generate gases , such as carbon dioxide and nitro Thermogenic hydrocarbons are generated in the subsur- gen , that can affect the formation pressure ); and / or increase face from source rocks rich in organic matter . Following the generation of biogenic gas in the formation . initial deposition , source rocks are buried and subjected to increasing temperature and pressure with increasing burial . While microbial stimulation techniques can be very use Thermogenic hydrocarbons are then generated when the 30 ful, it can be difficult to accurately monitor their perfor source rocks reach temperatures sufficient for the thermal mance . That is , it can be difficult to obtain an accurate in situ conversion of organic material to kerogen and then to free sample of the microbial community to test and evaluate their liquid and /or gaseous hydrocarbon phases in a process called performance. Further it can be difficult to predict which source rock maturation . Upon generation , the hydrocarbons microbial stimulation techniques will perform the best and may subsequently be expulsed from the soured rock and 35 how- differentmicrobial communities will react and perform migrated in the subsurface to reservoir rocks ( such as under the harsh environmental conditions deep in the sub sandstones or limestones ) that have sufficient porosity, struc surface , as it is difficult to replicate such conditions in a ture , and an adequate seal that make them capable of laboratory environment. trapping the hydrocarbon phase ( s ), allowing hydrocarbons The environmental conditions ( e . g ., temperature , pres to accumulate . 40 sure , formation water salinity , reservoir lithology , etc . ) of In contrast to thermogenic hydrocarbons which are gen - reservoir formations and coalbed systems can vary signifi erated during source rock maturation processes , biogenic cantly . The structure of microbial communities ( e . g . , the hydrocarbons are generated as byproducts from microbial type of microorganisms that are present in the community utilization of buried organic matter in the subsurface . The and their relative proportion of the total microbial popula generation of biogenic hydrocarbons usually occurs early 45 tion ) are very sensitive to the environmental conditions as during sediment burial ( e . g . , primary biogenic gas genera different microbial species have different tolerances for tion ), but can also occur during the degradation of ther - temperature , salinity , and nutrient supplies. For example , mogenic hydrocarbons , for example as a byproduct of microbial communities that exist in shallow reservoirs with microbial consumption of thermogenic hydrocarbons ( e . g ., fresh formation water are likely different from those that secondary biogenic gas generation ) . 50 prevail at deeper, warmer reservoirs with higher salinity Conventional pressure depletion methods that are used to formation water. produce oil from subsurface accumulations typically result Further, in MEOR and MECOM techniques that involve in only modest recovery factors . Often , approximately the introduction of nutrients to the formation to stimulate 60 -80 % of the oil in the subsurface remains inaccessible indigenous microorganisms, the process of stimulating the when such conventional pressure depletion production ends. 55 indigenous microbes can be unpredictable . For example, the As such , enhanced recovery methods, such as microbial growth of the microbial community can produce beneficial enhanced oil recovery (“ MEOR ” ) techniques, are then used effects by , for example , dislodging oil entrapped within the to try to access the residual oil to extend the life of the formation . However , alternatively , the grown of the micro production field . bial community can lead to increased consumption of light Similar challenges exist when producing biogenic gas 60 oils (e . g ., short - chain alkanes ) which can make the oil more fields that are present within coal seams or are sorbed to coal viscous and , thus , lower the recovery factor . ( . e. , coalbed methane ). In such systems, biogenic gas is Thus, there remains a need formethods and techniques to generated by the microbial degradation of the coal. How evaluate the efficiency and efficacy of microbial stimulation ever, over time the biogenic gas generation can decrease and operations. In particular , there remains a need for methods the recovery factor can decrease . Similar to MEOR tech - 65 and techniques for monitoring and evaluating the relative niques , stimulation of the microbial populations in these performance of different stimulation operations, for deter coal systems can be undertaken to regenerate the microbial mining whether appropriate stimulation treatments are being US 10 , 132 , 144 B2 employed for a given environment, and for determining DESCRIPTION OF THE FIGURES whether an optimized frequency of treatments is being utilized . FIG . 1 is a flow diagram of an exemplary method of using Background references may include US Patent Applica - isotopic signatures to monitor microbial stimulation of a tion Publication Nos. US 2014 /0250999 A1, and US 2014 / 5 well . 0288853 A1 : PCT Publications WO 2007 / 008932 A2 , WO FIGS . 2 and 3 are exemplary isotopic signatures that can 2013 /071187 A1, WO 2013 / 071189 A1, WO 2016 /043980 be utilized for determining the effectiveness of a microbial A1, WO 2016 /043981 A1 , WO 2016 /043982 A1 , WO 2016 / stimulation . 126396 A1, and WO 2016 / 126397 Al; and Bryant et al . ( 1989 ) “ Review ofMicrobial Technology for Improving Oil 10 DETAILED DESCRIPTION OF THE Recovery ” , SPE Reservoir Engineering , Vol. 4 , pp . 151- 154 ; DISCLOSURE and Van Hamme et al. ( 2003 ) “ Recent Advances in Petro Various specific embodiments , versions and examples of leum Microbiology ” , Microbiology and Molecular Biology the invention will now be described , including preferred Reviews, Vol. 67 , No. 4 , pp . 503 - 549; and SanareaSandrea et al. 15 embodiments and definitions that are adopted herein for ( 2007 ) “ Global Oil Reserves — Recovery Factors Leave Vast purposes of understanding the claimed invention . While the Target for EOR Technologies” , Oil & Gas Journal, Vol. 105 , following detailed description gives specific preferred pp . 44 - 47 ; and D . Hohl et al. ( 2010 ) “ Energy, Environment embodiments , those skilled in the art will appreciate that and Climate Directorate White Paper " , DCO Energy, Envi these embodiments are exemplary only , and that the inven ronment, and Climate Workshop , pp . 1 - 38 ; and G . Hassan - 20 tion can be practiced in other ways . For purposes of deter zadeh et al. ( 2011 ) “ Petroleum System Analysis Using mining infringement, the scope of the invention will refer to Geochemical Studies, Isotope and 1D Basin Modeling in any one or more of the appended claims, including their Hendijan Oil Field , SW Iran ” , International Petroleum equivalents, and elements or limitations that are equivalent Technology Conference , 14797 , pp . 1 - 11 ; and Li et al. (2014 ) to those that are recited . Any reference to the “ invention ” “ Microbial Abundance and Community Composition Influ - 25 may refer to one or more , but not necessarily all , of the ence Productionn Performance inin a Low - TemperatureTemperature Petro - inventions defined by the claims. leum Reservoir ” Environmental Science & Technology , Vol. Exemplary methods described herein may be better appre 48 , pp . 5336 -5344 ; and D . A . Stopler ( 2014 ) “ New Insights ciated with reference to flow diagrams. While for purposes Into the Formation and Modification of Carbonate -Bearing of simplicity of explanation , the illustrated methodologies Minerals and Methane Gas in Geological Systems Using330 30 may be shown and described as a series of blocks, it is to be Multiply Substituted Isotopologues ” , California Institute of appreciated that the methodologies are not limited by the order of the blocks, as some blocks can occur in different Technology Thesis , pp . 1 -305 ; and Stopler et al. (2014 ) orders and / or concurrently with other blocks from that “ Formation temperatures of thermogenic and biogenic shown and described . Moreover , less than all the illustrated methane ” , Science , Vol. 344 , pp . 1500 - 1503 ; and Stopler et 35 blocks may be required to implement various embodiments al . ( 2015) “ Distinguishing and understanding thermogenic of an example methodology . Blocks may be combined or and biogenic sources of methane using multiply substituted separated into multiple components . Furthermore , additional isotopologues” , Geochimica et Cosmochimica Acta , Vol. and / or alternative methodologies can employ additional 161, pp . 219 - 247 ; and Wang et al. ( 2015 ) “ Nonequilibrium blocks not shown herein . While the figures illustrate various clumped isotope signals in microbial methane ” , Science , 40 actions occurring serially , it is to be appreciated that various Vol. 348 , pp . 428 -431 . actions could occur in series , substantially in parallel , and / or at substantially different points in time. SUMMARY Various terms as used herein are defined below . To the extent a term used in a claim is not defined below , it should The methods and techniques described herein are directed 45 be given the broadest possible definition persons in the to methods of producing hydrocarbons. The methods may pertinent art have given that term as reflected in at least one generally comprise obtaining one or more samples from a printed publication or issued patent. well in a region of interest ; analyzing the one or more As used herein , the term “ basin modeling ” refers gener samples to determine a baseline isotopic signature , where ally to any method or analysis which provides a represen the baseline isotopic signature comprises one or more of 50 tation of the history of a sedimentary basin or other subsur multiply substituted isotopologues signatures, clumped iso face section of interest and / or an estimate of timing of any tope signatures , and position -specific isotope signatures ; component of a hydrocarbon system . For example , a basin performing a microbial stimulation operation on the region model may be used to model, but is not limited to , a burial of interest ; obtaining one or more post -stimulation samples history , time a specific subsurface location or layer reached from the well ; analyzing the post -stimulation to determine 55 a certain temperature or maturity , time for how long a an induced isotopic signature , where the induced isotopic location was in a certain temperature range , timing of signature comprises one or more of multiply substituted expulsion , timing ofmigration , and / or timing of accumula isotopologues signatures, clumped isotope signatures , and tion . Generally a basin model is based on and / or constrained position - specific isotope signatures ; comparing the baseline by measured or derived data representing present day con isotopic signature and the induced isotopic signature ; and 60 ditions ( e . g ., stratigraphy, current bottom hole temperature , determining whether the type of hydrocarbons ( e . g ., ther - heat flow ) or a condition in the past ( e . g ., water depth ) on mogenic hydrocarbons, biogenic hydrocarbons, or induced which a model of the past history of the area of interest is biogenic hydrocarbons ) being produced by the well has based . The calculations used to form the basin modelmay be changed . performed using a processor or other computer system . These and other features, aspects , and advantages of the 65 As used herein , the term “ biosurfactants ” refers to amphi present disclosure will become better understood with philic compounds produced on or by living surfaces , mostly regard to the following description and appended claims. microbial cell surfaces, or excreted extracellularly and con US 10 , 132 , 144 B2 tain hydrophobic and hydrophilic moieties that reduce sur ing hydrocarbons from a well or other opening . Hydrocar face tension and interfacial tensions between individual bon production normally refers to any activity conducted in molecules at the surface and interface , respectively . The or on the well after the well is completed . Accordingly , biosurfactants referred to herein are produced by the micro hydrocarbon production or extraction includes not only organisms in a reservoir or coalbed formation , and may be 5 primary hydrocarbon extraction but also secondary or ter of use in emulsification and de - emulsification of crude oils tiary production techniques , such as injection of gas or liquid through reduction of interfacial tension , and thereby aid in for increasing drive pressure , mobilizing the hydrocarbon or reducing the viscosity of the crude oil. Exemplary biosur treating by , for example chemical or hydraulic fracturing the factants may include peptides , fatty acids , phospholipids, wellbore to promote increased flow , well servicing, well glycolipids, lipopepties, etc . Exemplary biosurfactants may 10 logging , and other well and wellbore treatments . have one of the following structures : mycolic acid , glyco - As used herein , the term “ isotope” refers to one of two or lipids, polysaccharide - lipid complex , lipoprotein or lipopep more atoms with the same atomic number but with different tide, phospholipid , or the microbial cell surface itself . Bio - numbers of neutrons . Hydrocarbon molecules generally surfactants that may be of particular use in the present contain both carbon and hydrogen atoms and may contain a application may include , but not be limited to , emulsan , 15 variety of isotopes . For example, each carbon atom in a alasan , surfactin , rhamnolipid , lichenysen , glycolipids, vis - hydrocarbon molecule can be present as one of two stable cosin , trehaloselipids, sophorolipids, peptidolipid , and mix - isotopes: 12C , which has 6 protons and 6 neutrons, and /or tures thereof. 13C , which has 6 protons and 7 neutrons . Similarly , each As used herein , the term “ biopolymer” refers to a polymer hydrogen atom in a hydrocarbon molecule can be present as produced by a microorganism . In general, exemplary biopo - 20 one of two stable isotopes: H , which contains 1 proton and lymers may include polysaccharides, polyesters, poly - no neutrons , and /or deuterium ( D ), which has 1 proton and amides, etc . Particular biopolymers that may be of use in the 1 neutron . As another example , helium can be present as one present application may include, but not be limited to , of two stable isotopes : ? He , which has 2 protons and 1 xanthan , pullulan , levan , curdlan , dextran , sleroglucan , alg - neutron , and /or " He, which has 2 protons and 2 neutrons . inate , and mixtures thereof. The biopolymers referred to 25 As used herein , the term “ isotopologues ” refers generally herein may be of particular use in modifying the injectivity to molecules that have the same chemical composition , but profile and viscosity of crude oils and other formation fluids. have a different isotopic signature . For example , methane As used herein , “ community composition ” refers to the contains one atom of carbon and four atoms of hydrogen . composition of organisms in the system . That is , the com - Thus , each atom in the methane structure can contain one of munity composition is an indication of the types or organ - 30 the two stable isotopes of that atom , and as such there are ten isms ( e . g ., bacteria vs . archaea , or species X vs. species y possible isotopologues of methane . that live or exist in the system . As used herein , the term “ multiply substituted isotopo As used herein , “ community structure ” refers to the logues ” refers generally to an isotopologue that contains at abundance of each type of organism in the system . In least two rare isotopes in its structure . For example , a particular, the community structure is an indication of the 35 multiply substituted methane isotopologue may contain one relative abundance of the different types of organisms in the 3C atom and one D atom , or at least two D atoms and no system . For example , the community structure may indicate 3C atom . that the system comprises 10 % bacteria and 90 % archaea . In As used herein , the term “ clumped isotopologue ” refers some embodiments , the community structure may look at generally to an isotopologue that contains at least two rare only a subset of the organisms within the system and provide 40 isotopes that share a common chemical bond in its structure . an indication of the relative abundance of certain species For example , a clumped isotopologue of methane contains within the system as compared to other species within the one 13C atom that shares a chemical bond with at least one system . For example , the community structure may indicate D atom . that the system comprises 25 % species x , 40 % species y , As used herein , the term “ position specific isotope signa 30 % species z , and 5 % of unclassified species . 45 ture ” refers generally to a compound that has multiple As used herein , " exemplary ” means serving as an chemically or structurally distinct positions for a rare isotope example , instance , or illustration . Any embodiment to reside . For example , a position specific isotope signature described herein as exemplary is not to be construed as in propane could refer to the position of the 13C atom , which preferred or advantageous over other embodiments . can be positioned either at the center of the compound or one As used herein , the term “ fingerprint” or “ geochemical 50 of the end positions. Likewise , a position specific effect in fingerprint ” refers to a collection of signatures or geochemi- propane could refer to the position of a D atom , which could cal signatures that are associated with a particular region of be attached either to the central carbon or to one or more ) interest . of the end position carbons . As used herein , “ hydrocarbons” are generally defined as “ microbe” is any microorganism that is of the domain molecules formed primarily of carbon and hydrogen atoms 55 Bacteria , Eukarya , or Archaea . Microbes include bacteria , such as oil and natural gas . Hydrocarbons may also include fungi, nematodes, protazoans , archaebacteria , algae , dino other elements or compounds, such as , but not limited to , flagellates , molds, bacteriophages, mycoplasma, viruses, halogens , metallic elements , nitrogen , oxygen , sulfur, and viroids . hydrogen sulfide (H2S ) , and carbon dioxide (CO , ) . Hydro As used herein , the term “ region of interest ” refers to an carbons may be produced from hydrocarbon reservoirs 60 interval, compartment, or reservoir where hydrocarbons , through wells penetrating a hydrocarbon containing forma- non - hydrocarbon gases , and / or water may reside . Likewise , tion . Hydrocarbons derived from a hydrocarbon reservoir “ regions of interest " may refer to multiple intervals , com may include , but are not limited to , petroleum , kerogen , partments , or reservoirs where hydrocarbons, non -hydrocar bitumen , pyrobitumen , asphaltenes , tars , oils , natural gas, or bon gases , and / or water may reside . combinations thereof. 65 As used herein , the term “ inter- regional ” or “ inter -com As used herein , “ hydrocarbon production ” or “ producing p artment” refers to comparisons of multiple geochemical hydrocarbons ” refers to any activity associated with extract - fingerprints from multiple regions of interest including , but US 10 , 132 , 144 B2 not limited to , compartments , intervals , or reservoirs. Devia - oversupplied with nutrients ( e . g . , swamps or ponds ) are tions in “ inter -regional ” fingerprints may be derived from often not distinguishable from that of biogenic gases that are different proportions of individual regions or interest con - formed in the deep subsurface . tributing to a combined flow stream during production or Microbial stimulation of the deep subsurface to improve may be derived from multiple compartments that are con - 5 oil quality and / or assist in enhanced oil recovery operations nected in the subsurface that produce a fingerprint consistent results in the generation of biogenic gases. This “ induced ” with multiple inputs . biogenic gas is generated at faster rate ( as compared to the As used herein , the term " intra -regional ” or “ intra - com " naturally ” produced biogenic gases ) as the system is now partment” refers to comparisons of multiple geochemical oversupplied with nutrients ( similar to swamps and ponds at fingerprints derived from one region of interest including but 10 the surface ) . As such , the bulk isotopic signature of not limited to compartments , intervals , or reservoirs . Devia “ induced ” biogenic methane cannot be distinguished from tions in “ intra - regional” fingerprints may be derived from " naturally ” occurring biogenic methane . However, as changes in the properties of one region of interest such that described herein the multiply substituted isotopologue sig the fluids produced or processes occurring within one region natures , clumped isotope signatures , and / or position -specific of interest . 15 isotope signatures can be used to distinguish between the As used herein , the term “ organic acid ” refers generally to “ naturally ” occurring biogenic gas and the “ induced ” bio an organic compound with acidic properties . The organic genic gas. That is, natural subsurface biogenic and ther acids referred to herein are produced by the microorganisms mogenic gases have multiply substituted isotopologue sig in a reservoir or coalbed formation , and may be of use in natures, clumped isotope signatures, and / or position -specific increasing the permeability of a formation as well as increas - 20 isotope signatures that are at internal isotopic equilibrium ing emulsification . Organic acids that may be of particular and which can be used to provide information about the interest in the present application may include, but not be temperature at which the gas was generated . Microbial gases limited to , acetic acids, butyric acid , and propionic acid . that are generated by providing an oversupply of nutrients to As used herein , the term " stochastic distribution ” refers artificially stimulate rapid grown of the microbial commu generally to a system where the stable isotopes in a given 25 nity are characterized by a kinetic isotopic effect (KIE ) that population of molecules are distributed randomly among all is not at equilibrium , and thus do not correlate to the possible isotopologues of a given species . The stochastic temperature at which the gas was formed . distribution is the reference frame from which deviations are Given the differences in the multiply substituted isotopo measured and is used to provide a baseline to identify logue signatures, clumped isotope signatures , and / or posi anomalies that may be associated with secondary isotope 30 tion - specific isotope signatures from indigenous ther exchange processes. mogenic and biogenic hydrocarbons that are present in As used herein , the term “ signatures ” refers to the relative either trapped , unrecovered oil or as methane not produced abundances , concentrations , and / or ratios of various ele - from coals and the signatures of the induced biogenic gas , ments , isotopes , and /or isotopologues of a given species . For one can monitor the evolution and deviation in the signa example , a signature may be derived from the clumped 35 tures pre - and post- stimulation . The change in the gas isotopes within a sample . signature can then be used to quantify the amount of induced As used herein , the term “ thermogenic ” refers to hydro - hydrocarbons produced post - stimulation . This can then be carbons generated from kerogen that is currently / has in the used to compare differences in stimulation strategies ( e . g . , past been subjected to high temperature and pressure . introduction of different microbial communities and /or dif Described herein are methods and techniques that utilize 40 ferent nutrient supplies ) . Also , because gas moves quicker molecular geochemistry and isotopic signatures to monitor than oil in the subsurface , monitoring this induced signature microbial enhanced gas and oil recovery operations. For can be used to determine when re -stimulation may be example , the methods and techniques may monitor the needed in the oil producing system before the rate of oil multiply substituted isotopologue signatures, clumped iso production begins to decline for any given well . Addition tope signatures, and /or position - specific isotope signatures 45 ally , as MEOR operations can alter the quality of the oil , of one or more byproducts of microbial stimulation tech - changes in the oil quality pre - and post - stimulation can be niques . Exemplary byproducts that may be monitored monitored . include , but are not limited to hydrocarbons ( e . g . , methane ) , In addition to change in the hydrocarbon ( e . g . , methane ) biosurfactants , biopolymers, organic acids, and combina - signatures , changes in the isotopic signatures of the biosur tions thereof. For example , comparisons can be made 50 factants , biopolymers , and organic acids that are produced as between baseline isotopic signatures before stimulation and byproducts of the biogenic gas generation process can also induced isotopic signatures that occur after stimulation . The be used to monitor stimulation operations . For example, the methods can be utilized to determine which microbial com - multiply substituted isotopologue signatures , clumped iso munities perform better under a given set of environmental tope signatures, and / or position -specific isotope signatures conditions and / or which nutrient supplies give the best 55 of the biosurfactants , biopolymers , and organic acids may recovery factors . Further , the methods can also be utilized to change after a stimulation treatment due to being produced inform the frequency at which re - stimulation is necessary to under nutrient oversupply conditions. As another example , maintain a constant flow of hydrocarbons at a given well due to changing environmental conditions ( e . g . , tempera location . ture, pressure , and / or salinity ) in the reservoir or coalbed due Bulk isotopic signatures ( e . g . , abundance or concentration 60 to the stimulation operations, the indigenous microbial com of 81 % C and / or SD in a sample ) can typically be used to munity may shift to favor certain microorganisms over other identify methane formed naturally in the deep subsurface , microorganisms. As the microbial community shifts to favor such as at depths greater than 500 meters , and to distinguish different dominant species , the various biosurfactants , between methane formed from thermogenic sources and biopolymers , and organic acids that are produced may methane formed from biogenic sources . However, the bulk 65 change , and the isotopic signatures of the various biosur isotopic signatures of methane formed from biological pro - factants , biopolymers , and organic acids that are produced cesses in a laboratory or in subsurface environments that are may also shift . Similarly , if the stimulation operation US 10 , 132 , 144 B2 10 involves the introduction of exogenous microorganism to tures. In addition to the size of the signatures , the time the well, this may also cause changes in the isotopic signa required for these processes to affect the signature may also tures of the various biosurfactants , biopolymers , and organic differ from compound to compound . Integration of mea acids that are produced as different microbial populations in sured multiply substituted isotopologue signatures, clumped the community are stimulated . 5 isotope signatures, and /or position - specific isotope signa Isotopologue geochemistry is based on the variation in the tures of multiple hydrocarbon species with an understanding distribution of isotopes within a molecule that give rise to of the kinetic properties of these species provides unique molecules that are identical in their elemental composition , constraints on both the temperature at which the compounds but that may differ in the isotopic composition of individual is generated and /or stored in the subsurface . Kinetic prop atoms within that molecule . These species are called isoto - 10 erties of multiply substituted isotopologue signatures , pologues. For example , there are three isotopologues of clumped isotope signatures, and /or position - specific isotope nitrogen (14N , 15N -14N , and I9N _) . An isotopologue in signatures may be derived from laboratory experiments or which two or more rare isotopes are present is called a modeling approaches as described in further detail below . multiply substituted isotopologue , and an isotopologue in As an example, some hydrocarbon species may develop a which two or more rare isotopes are in close proximity (i . e ., 15 signature that does not change over geologic timescales of isotopic “ clumps " ) is called a clumped isotope ( e . g . , " N ) . billions of years if conditions or reactions change . One Hydrocarbon isotopologues involve hydrocarbon com example of this is methane , which is believed to develop a pounds ( i . e . , those that comprise carbon and hydrogen multiply substituted isotopologue signature that is domi atoms) that have natural isotopes of 12C , 13C , ' H , or deu nantly sensitive to temperature . This signature appears to terium ( D ) . Similarly isotopologues of biosurfactants ( e . g ., 20 develop during generation of the methane molecule and is lipids ) , biopolymers , and organic acids can involve the then locked in even if the methane molecule is transported natural isotopes of 12C , 3C , ' H , or deuterium (D ). 12C to a colder environment and stored . In contrast , other represents about 98 .93 mole % of the total carbon on Earth , hydrocarbon molecules are sensitive to temperature may while 13C forms the remaining 1 . 07 mole % . The isotopic track changes in temperature over short timescales . For abundance of ' H on earth is 99 .985 mole % while D has an 25 example , decane may initially develop a signature that abundance of 0 . 015 mole % . Thus , common volatile hydro - records the temperature at which it was generated , but this carbons can have large numbers of stable isotopologues signature may subsequently change to reflect increases or ( e . g. , methane has 10 , ethane has 36 , and propane has 216 ) . decreases in the temperature at which the compound resides As an example , two common isotopologues of methane over timescales of years . Another example may be that for include 13CH2D or 12CH . Similarly, numerous stable iso - 30 some isotopologues , the isotope positions within molecules topologues of different biosurfactants , biopolymers , and / or are sensitive to biodegradation and , if an understanding of organic acids can exist. the time taken to biodegrade the particular compound is In addition to the number of rare isotopes, the distribution possible one can determine how long the hydrocarbon has of isotopes in the molecule can also provide information been undergoing biodegradation . Thus , by measuring the about the molecule . For example , in a linear hydrocarbon 35 multiply substituted isotopologue signatures , clumped iso compound with three carbon atoms, the rare isotope can tope signatures, and /or position -specific isotope signatures either take a central or terminal ( end of the molecule ) of multiple hydrocarbon compounds that are be sensitive to position . Similarly , rare isotopes of hydrogen can occupy different parameters ( e . g ., temperature and /or pressure ) and different positions . As the size of the hydrocarbon or have different rates of reaction ( i. e ., different rates of molecular compound increases , the number of positions that 40 exchange between the different isotopologues ) , different these rare isotopes can be situated increases. This effect is information about the history of the hydrocarbon may be called the position specific isotope effect, or isotopomer determined following generation of the hydrocarbon . geochemistry . The present techniques take advantage of isotopmer geo The multiply substituted isotopologue signature , clumped chemistry and the rapid evolution of induced biogenic gases isotope signature , and / or position - specific isotope signature 45 after microbial stimulation to distinguish “ induced ” gases of any molecule is a function of ( i ) temperature - independent and newly formed byproducts from those that existed pre randomly populated processes ( stochastic distribution ) and stimulation . Accordingly , the methods and techniques pro ( ii ) other non - random mass fractionating processes . The vide for methods and techniques to enhance reservoir sur stochastic distribution of any isotopologues can be deter - veillance or monitor the production of a well, and /or to mined from the bulk isotope signature of the species from 50 provide a unique characterization of hydrocarbons and other which it derives . For example , determining the stochastic byproducts that are produced before and after microbial distribution of isotopologues for methane involves knowl stimulation . That is , themeasurement of multiply substituted edge of the 13C and D signatures ofmethane . At equilibrium , isotopologue signatures, clumped isotope signatures, and /or a non - stochastic distribution may result from thermody position -specific isotope signatures of the byproducts (such namic differences between the different isotopologues . 55 as hydrocarbons , biopolymers , biosurfactants , and organic Under non - equilibrium conditions, the non - random pro - acids ) of microbial stimulation can provide an understanding cesses may result be temperature - time dependent isotopic of the generation of hydrocarbons, such as liquids or gases , exchange reactions in the molecule . from the stimulation process . Further , the measurement of Additional equilibrium or non -equilibrium kinetic isotope multiply substituted isotopologue signatures, clumped iso exchange processes may also influence the signatures in 60 tope signatures , and / or position - specific isotope signatures some molecules , such as hydrocarbons. These processes can provide information about the generation , storage, and may include, but are not limited to , biodegradation , second alteration of the produced hydrocarbons . ary thermal cracking of hydrocarbons, thermochemical oxi Therefore , the present methods and techniques involve dation /reduction , reactions , mixing , or diffusion . These pro - measuring multiply substituted isotopologue signatures , cess may differ in their relative magnitude of the impact on 65 clumped isotope signatures, and /or position -specific isotope the multiply substituted isotopologue signatures , clumped signatures of one or more byproducts of microbial stimula isotope signatures, and / or position - specific isotope signa- tion . For example , the methods may involve measuring and US 10 , 132 , 144 B2 11 12 comparing pre - and post- stimulation isotopic signatures of signature even when exposed to different temperatures dur hydrocarbon samples, such as methane , or of biosurfactants , ing migration or uplift of the sediments in which the biopolymers , and organic acids in the produced fluids , as methane is contained . further described with reference to FIG . 1 . However, if the signature is shown to be outside the range FIG . 1 is a flow diagram of an exemplary method to 5 of an equilibrium signature , or appears to be unrelated to monitor the effects of a microbial stimulation on a produc - temperature , then other fractionating processes should be tion well , reservoir , or coalbed . This method may be used as considered . These may include alteration processes , such as part of a field deployable system , and / or as part of a reservoir biodegradation , secondary cracking of hydrocarbons , or surveillance program . The analysis based on such monitor - other processes , such as the results of a microbial stimula ing may be used to adjust or modify the microbial stimula - 10 tion as described herein . tion operations or hydrocarbon production operations . The application of multiply substituted isotopologue sig At block 102 one or more samples from a subterranean natures , clumped isotope signatures , and / or position - specific formation are obtained . For example , the sample may be isotope signatures to determine temperatures involves the obtained from a wellbore , such as a wellbore of a producing equilibrium relationship being known . This can be deter or exploration well . The sample can be in the form of 15 mined in several methods, which include experimental produced fluids, oil and / or gas obtained from the subsurface , information , theoretical or computed information , and a and / or as a rock sample with hydrocarbons entrapped combination of both . First , as in the above example regard therein . The produced fluids may include hydrocarbons and ing methane , laboratory experiments which measure the other non - hydrocarbon fluids produced from the subsurface . temperature and the compositions at equilibrium are both The sample may also contain various biosurfactants , biopo - 20 determined . The compositions are combined into approxi lymers , and organic acids. The samples are then analyzed for m ate ( ideal gas ) equilibrium " constants ” ( they vary with a geochemical signature , which includes a background iso - temperature , but not pressure or composition ), which can topic signature . The background isotopic signature com - then be used along with bulk compositional information prises one or more of a multiply substituted isotopologue ( D / H , 13C / 12C ), to determine the equilibrium isotopic com signatures , clumped isotope signatures, and / or position - 25 position for any temperature or the temperature for any specific isotope signatures . This background isotopic signa - equilibrium composition . The distribution of isotopologues ture can be used to develop a baseline isotopic signature for in a sample can bemeasured in the laboratory by any method any background concentration of one or more of hydrocar - or methods commonly used to measure composition , such as bons, biosurfactants , biopolymers , and organic acids within mass spectrometry , infrared and /or Raman spectroscopy , gas the formation . In some preferred embodiments , the baseline 30 chromatography , nuclear magnetic resonance , etc. Isotopi isotopic signature includes an analysis of the relative pro - cally labeled species can be used , increasing the overall portion or concentration of the multiply substituted isoto - amounts of rare isotopes so that the concentrations of pologue 13CH2D as compared to other isotopes of methane naturally rare species can be measured more accurately . in the sample . Other than direct measurement of compositions, the equi The analysis of the hydrocarbon sample may involve 35 librium constants can be determined using properties of the determining the multiply substituted isotopologue signa - individual isotopologues and the equations of statistical tures, clumped isotope signatures, and /or position - specific mechanics. See , e . g ., D . MacQuarrie , StatisticalMechanics , isotope signatures . The measurement of the absolute abun - University Science Books , pp . 113 - 159 , (2000 ) . The equa dance of isotopologues or position of interest for any given tions of statistical mechanics relate properties of the indi hydrocarbon involves the knowledge of the molecular mass 40 vidualmolecules ( e . g . , vibrational frequencies, moments of or absorption spectra at which they are present, and hence inertia , etc . ) to partition functions ( or partition function involves knowledge of the actual identity of each possible ratios ) and the partition functions (or ratios ) of a collection isotopologue for that species. Measurement of the abun - of molecules related via a chemical or isotopic transforma dance of each isotopologue or fragment can be conducted tion equation to the equilibrium constants . Of course there using multiple techniques , such as mass spectrometry or 45 are various approximations available in statistical mechanics nuclear magnetic resonance . and different combinations of different properties of the As an example , one of the characteristics that impact the molecules may be used to determine the partition functions isotopologue signature of some hydrocarbons is the tem - or partition function ratios . perature of formation or storage . In particular, this tempera - The most commonly used method uses experimentally ture can be used to differentiate between different sources of 50 measured vibrational frequencies from infrared and /or hydrocarbons. This is done through first conversion of the Raman spectroscopy and other molecular properties inferred multiply substituted isotopologue signatures, clumped iso - from those spectroscopies. See e . g . , Urey, H . C ., et al. , tope signatures , and /or position - specific isotope signatures “ Some Thermodynamic Properties of the H 'H² , H²H2Mol to temperature ( e . g . , conversion of the concentration of the ecules and Compounds Containing the H ? Atom ” , J . Chemi isotopologue in the sample to temperature) . Temperature is 55 cal Physics, Vol. 1 , pp . 137 - 143 ( 1933 ) ; Bigeleisen and an equilibrium signature that can be predicted by molecular Mayer , “ Calculation of Equilibrium Constants for Isotopic modeling of equilibrium concentrations of multiply substi - Exchange Reactions” , J. Chem . Phys. , Vol. 15 , No . 5 , pp . tuted isotopologue or positional effects , or may be deter - 261- 267, ( 1947 ) ; and Richet , Bottinga , and Javoy, “ A mined empirically by measurements of signatures of a given Review Of Hydrogen , Carbon , Nitrogen , Oxygen , Sulphur , hydrocarbon compound at different temperatures either in 60 And Chlorine Stable Isotope Fractionation Among Gaseous the presence or absence of a catalyst to accelerate equilib - Molecules ” , Annual Reviews In Earth and Planetary Sci rium . Different hydrocarbon species have different rates of ences , Vol. 5 , pp . 65 - 110 ( 1977 ) . These methods use only the equilibration of their multiply substituted isotopologue sig - relatively few fundamental vibrational frequencies of the natures, clumped isotope signatures , and / or position - specific molecules , or the related harmonic frequencies (which are isotope signatures. For example , the 13CH3D isotopologue 65 properties of the potential energy surface of the molecules in methane may record methane generation temperature and which are inferred from the experimental frequencies ( see, e . g . , Stolper et al. , Science ( 2014 )) and preserves the and other molecular properties ). A related method , less US 10 , 132 , 144 B2 13 14 dependent on approximations , uses substantially experimen III , “ Position - Specific and Clumped Stable Isotope Studies : tal information by directly summing partition function com Comparison of the Urey and Path -Integral Approaches for ponents from hundreds or thousands of vibrational/ rota Carbon Dioxide, Nitrous Oxide , Methane , and Propane” , J . tional spectroscopic lines. An example of such a method on Phys . Chem . A , Vol. 118 , pp . 467 -474 ( 2014 ). Ab initio the water molecule is provided by M . Vidler and J . Tenny - 5 Molecular Dynamics has been used to account for the son , " Accurate partition function and thermodynamic data influence of solvent fluctuations on isotopic fractionation by for water ” , J . Chem . Phys ., Vol. 113 , No. 21 , pp . 9766 - 9771 Rustad et al. See J . R . Rustad , E . J . Bylaska , V . E . Jackson , ( 2000 ). and D . A . Dixon , " Calculation of Boron -Isotope Fraction For convenience and because of the difficulty of obtaining ation Between B (OH ) 3 (aq ) and B (OH ) 2 (aq ) ", Geochimica accurate experimental information on the various isotopo - 10 et Cosmochimica Acta , Vol. 74 , pp . 2843 - 2850 ( 2010 ) . logues of a given molecular species, modern quantum Various options are available for the approximations and chemical calculations may also be used to provide the equations used from statisticalmechanics . Similarly, there is molecular properties , which are combined with statistical a large variety of " model chemistries” , which may be used mechanical equations to yield partition functions, partition to provide useful estimates of the molecular properties from function ratios , and /or equilibrium constants . Often , similar 15 computational quantum chemistry . The different methods or the same statistical mechanical equations are used as in may be distinguished by the use of ab initio theory or density the above methods , but the molecular properties and fre - functional theory . Themethods may also be distinguished by quencies are calculated from quantum chemical methods. different prescriptions for various physical and theoretical The most computationally efficient and commonly applied effects , such as electron exchange and correlation . The approach is to use the Urey or Bigeleisen -Mayer methods 20 selection of a “ basis set ” to describe the possible states of and to calculate " harmonic frequencies " . These are frequen - electrons may be useful. Different methods and equations cies, which are calculated from a harmonic oscillator ( qua may be chosen for computing a harmonically -corrected dratic potential function ) approximation of the interatomic molecular properties and for dealing with various forms of potential energy surface of the molecules. Several points on resonance interactions. The optimal combination ofmethods the potential energy surface are calculated directly from 25 may depend on the accuracy desired , the software and quantum chemical methods. Potentially more accurate computer hardware available, and the specific molecular results for the partition functions and equilibrium constants systems of interest . can be generated using computed anharmonic frequencies Position - specific isotope signatures are different than (which correspond to measured fundamental frequencies ) effects due to multiply substituted isotopologue signatures , and other properties of the molecules and their potential 30 but may be combined with other effects . The same theoreti energy surfaces . See , e . g ., Liu et al. , “ On the proper use of cal and computational methods may be used to compute the Bigeleisen -Mayer equation and corrections to it in the partition functions and equilibrium constants for position calculation of isotopic fractionation equilibrium constants ” , specific isotopologues and their conversion reactions . Geochimica et Cosmochimica Acta , Vol. 74 , pp . 6965 -6983 Experimentally , some methods are not able to differentiate ( 2010 ) . For some more complex molecules , physical and 35 between position - specific isotopomers . For example , mass computational effects such as " resonance ” are known to spectral methods that rely only on the parent molecular ion degrade the quality of the computed properties . These can do not contain useful information on the position of the partially be corrected using themethods discussed in Bloino different isotopic atoms. However, fragments of the molecu et al. , and as implemented in commercial quantum chemistry lar ion may contain such information . The mass spectrum software . See e. g . , J . Bloino , M . Biczysko, and V . Barone , 40 signals due to C2H5 + and CH3 + fragments of propane ( and “ General Perturbative Approach for Spectroscopy , Thermo - their 13C and D containing forms) are related to the relative dynamics, and Kinetics : Methodological Background and amounts of the position specific forms of propane; e . g . Benchmark Studies ” , J. Chem . Theory Comput. , Vol . 8 , pp . (H3C ) (CHD ) ( CH3) vs . (H3C ) (CH2 ) (CH2D ) . 1015 - 1036 (2012 ) . As an example , Wang et al. describes calculations of As an example , the methods of Bloino et al . may be used 45 partition function ratios and fractionation factors for various in the Gaussian 09 software (see , e . g . , Gaussian 09 , Revision positions in various functional groups for hydrocarbons and D .01 , Frisch et al. , Gaussian , Inc . , Wallingford Conn . other organic molecules using density functional theory with ( 2009) ) combined with the B3LYP density functional the B3LYP functional and the 6 - 311G * * basis set with method or MP2 post -Hartree Fock ab initio method and the further calibration to experiments on rapidly exchanging aug - cc -PVTZ basis set to compute anharmonic frequencies 50 hydrogen positions adjacent to the carbonyl group in and other molecular constants for methane . These can be ketones . See , e . g ., Y . Wang , A . L . Sessions , R . J. Nielsen , used with the simple perturbation theory of Truhlar et al. to and W . A . Goddard , III , “ Equilibrium 2H / 1H fractionations provide partition functions and these combined to produce in organic molecules : I. Experimental calibration of ab initio equilibrium constants . See , e . g ., Truhlar , D . G . and Isaacson , calculations " , Geochimica et Cosmochimica Acta , Vol. 73 , A . D ., " Simple perturbation theory estimates of equilibrium 55 pp . 7060 -7075 (2009 ) . constants from force fields” , J. Chem . Phys. , Vol. 94 ( 1 ) , pp . Time - dependent behavior of multiply substituted isoto 357 - 359 (1991 ) . Equations involving the equilibrium con - pologues, clumped isotopes , and /or position - specific iso stants and the bulk isotopic signatures for C and D can be topes arise because not every natural process achieves solved using standard linear equation solvers in a package equilibrium , even over geologic time- scales . Because such as Matlab ( see , e . g . , MATLAB , The Math Works , Inc ., 60 chemical reaction rates generally decrease with temperature , Natick , Mass ., United States) . for some processes, there exist “ closure ” or “ blocking ” Other computational methods may be used to provide temperatures. That is, closure or blocking temperatures are some or all of the information involved in predicting parti - temperatures above which equilibrium is achieved on the tion functions and equilibrium constants . For example , path time- scales of interest for a particular application , and below integralMonte Carlo methods may be used . These have been 65 which equilibrium is not achieved on the time- scales of applied to isotopic fractionation in methane and other mol- interest. For hydrocarbon systems analysis , if a sample ecules by Webb and Miller. See M . A . Webb and T . F . Miller , which includes hydrocarbons and related molecular species , US 10 , 132 , 144 B2 15 16 is cooled from some initially high temperature , the system any hydrocarbon compound to a range of temperatures with may achieve equilibrium at a relatively high temperature , or without the presence of a catalyst for different periods of but this equilibrium may be “frozen - in ' at the blocking time. See , e. g ., Stolper , D . A . et al. , (2014 ), “ Formation temperature and subsequent cooling does not re - set this temperatures of thermogenic and biogenic methane” , Sci equilibrium . The characteristic temperature determined from 5 ence , Vol. 344 , pp . 1500 - 1503 . The hydrocarbon compounds multiply substituted isotopologue signatures , clumped iso - taken from these different experiments are analyzed and its tope signatures , and / or position -specific isotope signatures kinetic properties can be determined for any given tempera on a particular molecular type may then indicate this block - ture based on how quickly equilibration is reached at dif ing temperature . ferent temperatures in each experiment. Methods used to determine the rates and temperature - 10 An alternative approach may be to use molecular mod dependence of isotope exchange reactions are related to eling to predict the timescales at which the multiply substi those used to determine equilibrium . That is , the overall tuted isotopologue signature and / or position specific isotope time - scale of interconversion as a function of temperature signature of any given hydrocarbon compound . can provide useful information . The methods ofmeasuring Based on data from either of these different approaches , chemical rates is known in the art . One of the difficulties that 15 a model can be developed to provide kinetic parameters for has to be overcome in the experimental determination of any hydrocarbon compound . From this model, a present day rates as applied to geochemical processes is that those signature can be corrected for any historical change in its processes may effectively occur over geological time -scales , signature based on changes in temperature over some period but not occur over laboratory time- scales . Sometimes of time to determine the signature , and from this a historical increased temperatures are used to increase the rates into a 20 temperature , for any hydrocarbon compound for any time of measurable range and then an attempt is made to extrapolate interest . the rates to the geological temperatures of interest . For Thus, using the above described methods one can deter example , the rates of hydrogen - isotope exchange reactions mine the background isotopic signature of the sample , that in hydrocarbons were investigated by Reeves et al. See , e . g ., utilizes one or more of multiply substituted isotopologue E . P . Reeves , J . S . Seewald , S . P . Sylva , “ Hydrogen isotope 25 signatures , clumped isotope signatures , and /or position exchange between n - alkanes and water under hydrothermal specific isotope signatures . The background isotopic signa conditions " , Geochimica et Cosmochimica Acta , Vol. 77 , pp . ture may be used to determine the temperature at which the 582- 599 ( 2012 ) . This extrapolation may be inaccurate and , hydrocarbons in the sample were generated or altered , which in addition , the relative rates of different processes may be can also be used to give an indication of the age of the different at different temperatures . For these reasons and 30 hydrocarbons in the sample . others , the theoretical and / or computational approaches may Returning to FIG . 1 , at block 104 microbial stimulation be used to determine estimates of rates . techniques are used to stimulate the reservoir . Any known Methods of computing estimates of rates are also well microbial stimulation technique may be used . Preferably the known in the art . See , e. g ., Transition State Theory , S . microbial stimulation technique comprises introducing vari Glasstone, K . J . Laidler , and H . Eyring, “ The Theory of Rate 35 ous reactants and / or nutrients into the subterranean forma Processes ” , McGraw -Hill , New York (1941 ) . The estimates tion , introducing exogenous microbial populations into the may be less accurate than those of isotopic equilibrium subterranean formation , and combinations thereof. phenomena ( e . g . , may only be accurate to within an order of In some embodiments , the microbial stimulation tech magnitude ), but the estimates may be useful for establishing n iques may involve the introduction of various reactants and approximations to blocking temperatures . Many of the same 40 nutrients into the subterranean formation . Any nutrients , choices of methods and parameters that are be made in reactants , and additives as known in the artmay be used . The computing equilibrium properties are necessary in comput- nutrients may be chosen to be those that are selectively ing rates via computational chemistry methods . desired by one or more of the microorganisms already Temperature is an equilibrium signature that can be present in the subterranean formation . That is , the nutrients predicted by molecular modeling of equilibrium concentra - 45 may be chosen to promote the growth of one or more of the tions of multiply substituted isotopologue or positional indigenous species (or one or more of the exogenous species effects , or may be determined empirically by measurements being injected ) over other indigenous species currently in of signatures of a given hydrocarbon compound at different the formation . This can allow for selective promotion of the temperatures either in the presence or absence of a catalyst microorganism that have desirable properties over others . to accelerate equilibrium . Different hydrocarbon species 50 In some embodiments , the microbial stimulation tech have different rates of equilibration in multiply substituted niques may involve the injection of an exogenous microbial isotopologues . For example , methane records methane gen - population into the subterranean formation . For example , an eration temperature and preserves this signature even when inoculating culture may be supplied with various nutrients exposed to different temperatures . In contrast, a molecule and additives to water or other fluids being pumped into a such as decane may give a temperature that reflects the 55 well in the formation . Any suitable microorganism may be temperature at which it has been stored over the past several used . However, care should be taken to choose a microor years because it can undergo intra -molecular isotope ganism that can survive in the conditions that prevail in the exchange over faster timescales than methane . Historical formation . That is , microorganisms should be chosen that temperatures obtained from the clumped or position specific can thrive in the formation despite any physical constraints , isotope signatures may be different for different species 60 such as small and variable formation pore sizes , and envi because each of these hydrocarbon compounds record dif- ronmental constraints , such as high temperature , high salin ferent parts of the history of the bulk hydrocarbon given ity , high pressure , and lack of oxygen , that are found in the their different kinetic behaviors . formation . Other biological constraints, such as competition The kinetic properties for different hydrocarbon com - from indigenous microbes and the stress of changing envi pounds can be determined through different approaches. 65 ronments ( e . g . ,moving from surface to subsurface ) may also One approach may be to determine kinetic parameters limit the viability of exogenous microorganisms. Various experimentally . This can be done, for example , by subjecting different microorganisms and combinations of microorgan US 10 , 132 , 144 B2 17 18 ism as known in the art may be used . Useful microorganisms In some embodiments , the induced isotopic signature may may include , but not be limited to , microorganisms from the be converted in a temperature , for example using the meth genera of Clostridium , Bacillus, Pseudomonas, Xanthomo ods described above for converting the baseline isotopic nas, Leuconostoc, Desulfovibro , Athrobacter, Corynebacte signature into a temperature. However, where the tempera rium , Enterobacter , and combinations thereof. Useful 5 ture of the baseline isotopic signature can indicate the microorganism may also include , but not be limited to , those formation or generation temperature of the hydrocarbons, selected from the following species : Bacillus lichenifornis ; the temperature of the induced isotopic signature is likely Leuconostoc mesenteroides; Xanthomonas campestris ; not at equilibrium as it was produced under oversupply of Acinetobacter calcoaceticus; Arthrobacter paraffineus; nutrient conditions in shorter time scales. Thus, a compari Bacillus licheniformis ; Clostridium pasteurianum ; Coryne - son of the temperatures of the pre - and post -stimulation bacterium fasciens; Pseudonomas rubescens; Bacillus poly - samples can give an indication of how effective the stimu myxa ; Brevibacterium viscogenes ; Clostridum acetobutyli - lation techniques are . That is , if the post- stimulation samples cum ; Zymomonas mobilis ; Enterobacter aerogenes ; exhibit an isotopic signature and formation temperature that Clostrodium acetobutylicum ; Enterobacter aerogenes ; and 15 are similar to the pre - stimulation samples, one can tell that combinations thereof. the stimulation techniques have not been effective . The exogenousmicrobial populations may also be chosen The induced isotopic signature can provide information to effect certain properties of the hydrocarbon recovery . For about how effective the stimulation techniques have been . example , when seeking to decrease the interfacial tension or For example , in FIG . 2 an increase in thermogenic hydro reduce the viscosity of the hydrocarbons in the formation , 20 carbon signatures (the rapid response ) can indicate that the microorganisms that are known to be good producers of stimulation technique has been effective at releasing trapped biosurfactants may be chosen . For example , Acinetobacter thermogenic hydrocarbons that had been trapped in pores or calcoaceticus ; Arthrobacter paraffineus ; Bacillus lichenifor - sorbed to the organic matrix in the formation . This can be mis ; Clostridum pasteurianum ; Corynebacterium fasciens; compared with the increase in production of the biogenic Pseudomonas rubescens , and combinations thereof may be 25 hydrocarbon signatures ( the sustained response ) which can used . Alternatively , when seeking to increase the permeabile indicate that the stimulation technique has been effective at ity of the formation and improve the emulsification of the creating new biogenic hydrocarbons and releasing any pre hydrocarbons , microorganisms that produce organic acids viously trapped biogenic hydrocarbons. By examining the ( e . g . , acetate , butyrate ) as by - products may be desired . For multiply substituted isotopologue signatures , clumped iso example , various species of Clostridum may be used , or 30 tope signatures , and /or position - specific isotope signatures Enterobacter aerogenes . of the biogenic gas signatures, one can further tell if they are At block 106 a sample is taken after the stimulation . The newly created biogenic gases from the stimulation tech post- stimulation sample is analyzed for the induced isotopic niques or if they are pre -stimulation biogenic gases. signature . The methods described above that are used to FIG . 3 provides an example of a schematic for prediction determine the background isotopic signature can be used to 35 a rapid response shift in the inferred temperatures due to determine the induced isotopic signature . Then , at block 108 increased induced biogenic gas production , a shift in the induced isotopic signature is compared to the baseline or inferred temperatures with a gradual return to background background isotopic signature . temperatures ( the sustained response ) , and rapid shift in The time interval between sample acquisition , measure - inferred temperatures with a gradual return followed by an ment, and analysis can have numerous valuable reservoir 40 increase associated with additional thermogenic gas release . surveillance and well monitoring applications . For example , Also as illustrated in FIG . 3 , as the shifts in the isotopic daily logs of induced isotope signatures collected during the signatures return the baseline levels this can indicate that a stimulation operations can be utilized to provide information re - stimulation techniques is needed . on the efficiency of the stimulation techniques. An example Returning to FIG . 1 , at block 110 , one or more additional of this could be that over time the effect from the stimulation 45 samples are optionally obtained at later times . These addi may decrease and thus the induced isotopic signature will tional samples can be analyzed to determine how the begin to converge back to the baseline isotopic signature induced isotopic signature changes over time. For example , over time. If this occurs , the production operation may be the additional samples may be obtained at specific time adjusted to perform another microbial stimulation . Another intervals , such as every hour, or every 1 to 3 hours , or every example may include monitoring of real - time or concurrent 50 5 to 24 hours , or every 24 to 72 hours, or weekly. As multiply substituted isotopologue , clumped isotope , and /or described above , using multiple samples can create a log of position -specific isotope data from analysis of co -mingled the isotopic responses from the microbial stimulation that hydrocarbons in a production stream to identify changes in can be used to evaluate the effectiveness of the stimulation the hydrocarbon signature that is associated with the stimu - techniques . lation operations . This information could suggest that the 55 At block 114 , the production or stimulation strategy may pressure is being drawn down in one region and has resulted be refined or modified . For example , the results of the in a decreased contribution . Similarly , this information could comparisons made at blocks 108 and /or 112 may be used to suggest that the nutrient supply is decreasing and has support decisions regarding whether re -stimulation is resulted in the microbial community reverting back to the needed , or whether the stimulation strategy needs to be baseline production . This information could then be used to 60 modified . For example , if after multiple stimulation proce change the stimulation strategy ( e . g . increase the addition of dures the spikes in the thermogenic hydrocarbon responses certain nutrients over others) to ensure long term fluid are decreasing , this can indicate that the vast majority of the production and maximize the lifespan of the well. These trapped hydrocarbons have been released . As such , any new measurements therefore provide a more cost effective and stimulation techniques may want to focus on the creation of rapid methodology , and allow for early identification of the 65 new biogenic gases . Alternatively, if after a stimulation performance of the stimulation operations that current moni- procedure the isotopic responses indicate that there is only toring methodologies do not allow . an increase in biogenic gas production , a new stimulation US 10 , 132 , 144 B2 20 procured may be contemplated that would instead enhance signature may be used to distinguish the thermogenic hydro the release of trapped thermogenic hydrocarbons . carbons from the biogenic hydrocarbons. However, by ana At block 116 the strategies may then be used to produce lyzing the differing clumped isotope signatures , multiply hydrocarbons. Producing hydrocarbon may include opera substituted isotopologue signatures , and / or position specific tions such as hydrocarbon extraction , along with injection of 5 isotopologue signatures , one may be able to compare the gas or liquid for increasing drive pressure , mobilizing the efficiency and effectiveness of different simulations recipes hydrocarbon or treating by , for example chemicals or over time. Larger deviations may suggest that more induced hydraulic fracturing the wellbore to promote increased flow , gas is generated . This may also correspond to larger volumes well servicing , well logging, and other well and wellbore of oil accessed and produced , thereby increasing the recov treatments 10 ery factor of the field . When the induced isotopic signature As an example scenario , the present methods and tech - deviation in the produced fluids begins to decrease , the field niques may be used with MECOM stimulation of coalbeds . can be re- stimulated . For example, a field that is producing coalbed methane may As described herein , the quantification of clumped iso begin to experience declines in the rate of methane produc - topes, multiply substituted isotopes, and / or position specific tion at producing wells . Prior to stimulation , the methane 15 isotope signatures of hydrocarbons can be used as part of a sampled at a producing well has an equilibrium methane reservoir surveillance or well monitoring program . The clumped isotope signature for primary biogenic gas. This signatures can provide diagnostic information regarding the equilibrium signature can be used to determine that the history of the hydrocarbons and therefore provide informa biogenic gas has a generation temperature of less than 80° C . tion regarding source , alteration , etc . MECOM is performed to stimulate the in - situ microbial 20 The methods and techniques described herein may utilize communities in the coalbed to generate more methane by a computer system . For example , the computer system may further biodegradation of the coal. Upon generation of the comprise a central processing unit (CPU ) that is coupled to induced methane , the induced methane mixes with the system bus. The CPU may be any general- purpose CPU , residual primary , inherited methane . Samples are taken from although other types of architectures of CPU may be used as the well over a period of time to identify when this induced 25 long as CPU supports the inventive operations as described methane arrives at the well bore , and how much induced herein . The CPU may execute the various logical instruc methane is produced relative to the original primary meth - tions according to various exemplary embodiments . For ane. The bulk carbon isotopes signature of the gases may not example , the CPU may execute machine- level instructions shift sufficiently with MECOM treatments to resolve the for performing processing according to the operational flow induced vs . inhereited biogenic gas , so long as the microbial 30 described above . community and /or metabolic pathways are relatively similar The computer system may also include computer com pre - and post - treatment. In this scenario , as the in -situ ponents such as a random access memory (RAM ) , which microbial community is stimulated , it is likely that the may be SRAM , DRAM , SDRAM , or the like . The computer metabolic pathways pre - and post - treatment will be similar, system may also include read -only memory (ROM ) , which and thus , that the bulk isotopic composition of the methane 35 may be PROM , EPROM , EEPROM , or the like . RAM and will be similar for both sources of gas. However, in contrast , ROM hold user and system data and programs, as is known the relative concentrations of the clumped isotopes ,multiply in the art . The computer system may also include an substituted isotopologues , and / or position specific isotopo - input/ output ( I / O ) adapter , GPU ( S ) , a communications logues of the methane will change after treatment because adapter, a user interface adapter , and a display adapter. The the microbial processes were driven to excess post - treatment 40 1 / 0 adapter , the user interface adapter , and / or communica by excess reactants and nutrients . This produces a large KIE tions adapter may , in certain embodiments , enable a user to in the induced methane . Therefore , analysis of methane interact with computer system in order to input information . sampled from the well post- treatment can be used to quan - The I / O adapter preferably connects a storage device ( s ) , tify how much induced methane is present in the gas such as one or more of hard drive , compact disc (CD ) drive , mixture . This approach can also be used to test different 45 floppy disk drive , tape drive , etc . to computer system . The mixes of nutrient supplies in the stimulating fluid to see storage device ( s ) may be used when RAM is insufficient for which mixes generate the largest gas induced volumes . This the memory requirements associated with storing data for approach can also be used to identify the period of time over operations of embodiments of the present techniques . The which the induced methane continues to be produce . By data storage of the computer system may be used for storing doing this , the operator can develop the most effective 50 information and / or other data used or generated as disclosed nutrient supply and program of stimulation frequency to herein . The communications adapter may couple the com optimize the generation and production of coalbed methane . puter system to a network ( not shown ) , which may enable As another example scenario , the present methods and information to be input to and / or output from system via a techniques may be used to improve recovery of oil in a network ( for example , the Internet or other wide - area net producing field using MEOR . For example , as the volume of 55 work , a local- area network , a public or private switched oil being produced from a well in an oil field starts to decline telephony network , a wireless network , any combination of and the total volume produced since the field began is the foregoing ). A user interface adapter couples user input approaching the estimated ultimate recovery factor for the devices , such as a keyboard , a pointing device , and the like, field , the well can be sampled to characterize the natural to computer system . The display adapter is driven by the background signature of the subsurface hydrocarbons . 60 CPU to control , through a display driver , the display on a MEOR is performed to stimulate a subsurface microbial display device . Information and / or representations pertain community that can access and mobilize currently unpro - ing to a portion of a supply chain design or a shipping ducible oil in the subsurface . The MEOR process produces simulation , such as displaying data corresponding to a induced biogenic methane as a by -product , and may also physical or financial property of interest , may thereby be alter the organic acids and biosurfactants in the well ' s 65 displayed , according to certain exemplary embodiments . produced fluids. The induced biogenic methane mixes with The architecture of system may be varied as desired . For the indigenous thermogenic hydrocarbons . The bulk isotopic example , any suitable processor - based device may be used , US 10 , 132 , 144 B2 21 22 including without limitation personal computers, laptop construed as encompassing all the features of patentable computers , computer workstations , and multi- processor novelty which reside in the present invention , including all servers . Moreover, embodiments may be implemented on features which would be treated as equivalents thereof by application specific integrated circuits (ASICs ) or very large those skilled in the art to which the invention pertains. scale integrated (VLSI ) circuits . In fact, persons of ordinary 5 The invention has been described above with reference to skill in the art may use any number of suitable structures numerous embodiments and specific examples . Many varia capable of executing logical operations according to the tions will suggest themselves to those skilled in this art in embodiments . light of the above detailed description . All such obvious As an example , machine- readable logic or code may be variations are within the full intended scope of the appended used or executed with a computing system . The code or a set 10 claims. of instructions is provided enhancing hydrocarbon produc tion operations , which may include analyzing hydrocarbon The invention claimed is : samples for geochemical signature comprising clumped 1 . A method of producing hydrocarbons comprising : isotope signature , multiply substituted isotope signature , ( a ) obtaining one or more samples from a well in a region and / or position specific isotope signatures . When executed 15 of interest ; or applied with a computer system , such as computer ( b ) analyzing the one or more samples to determine a system , code or set of instructions is configured to : analyze baseline isotopic signature , wherein the baseline isoto one or more of hydrocarbon samples from the subsurface pic signature comprises one or more of multiply sub formation for a baseline geochemical signature , wherein the stituted isotopologue signatures , clumped isotope sig baseline geochemical signature is based on clumped isotope 20 natures , and position - specific isotope signatures ; signature , multiply substituted isotopologue signature, and / ( c ) performing a microbial stimulation operation on the or position specific isotope signature ; analyze one or more region of interest ; hydrocarbon samples obtained from the subsurface location ( d ) obtaining one or more post- stimulation samples from at a time after a microbial stimulation operation for a the well; induced geochemical signature , wherein the induced geo - 25 ( e ) analyzing the post -stimulation sample to determine an chemical signature is based on clumped isotope signature , induced isotopic signature , wherein the induced isoto multiply substituted isotopologue signature , and /or position pic signature comprises multiply substituted isotopo specific isotope signature ; and compare the induced geo logue signatures , clumped isotope signatures , and /or chemical signature with the baseline geochemical signature . position - specific isotope signatures ; In addition , the set of instructions may be configured to 30 (f ) comparing the baseline isotopic signature and the provide other enhancements . For example , the set of instruc induced isotopic signature; tions may be further configured to : adjust a production or ( g ) using the comparison to determine whether the type of stimulation strategy based on the comparison . Also , the set hydrocarbons being produced from the well has of instructions may be further configured to : convert each changed , wherein the type of hydrocarbons being pro baseline geochemical signature into a baseline temperature ; 35 duced from the well comprises thermogenic hydrocar and convert the induced geochemical signatures into an bons, biogenic hydrocarbons, and induced biogenic induced temperature , and compare the induced temperature hydrocarbons; and with the baseline temperature . Further, the set of instructions (h ) updating or refining the microbial stimulation opera may be further configured to : identify a source contribution tion based on the type of hydrocarbons being produced for the induced geochemical signature based on the baseline 40 from the well . geochemical signature . 2 . The method of claim 1, wherein the sample comprises In addition , the set of instructions may be further config - produced fluids from the well. ured to : detect of elevated or decreased hydrocarbon pres- 3 . The method of claim 1, wherein the sample comprises ence ; and transmit a notification to a field deployable system hydrocarbons . to obtain a sample from the subsurface location to analyze 45 4 . The method of claim 1 , wherein the sample comprises for an induced geochemical signature . The set of instructions one or more of biosurfactants , biopolymers , and organic may be further configured to : monitor for changes in the acids. produced fluids of organic acids and biosurfactants ; and /or 5 . The method of claim 1 , wherein the microbial stimu monitor for stable isotope geochemistry changes in the lation operation comprises introducing nutrients into the produced fluid in one or more of organic acids and biosur - 50 region of interest. factants . 6 . The method of claim 5 , wherein the nutrients comprise All patents and patent applications, test procedures ( such one or more of molasses, nitrates, vitamins, and surfactants . as ASTM methods, UL methods, and the like ), and other 7 . The method of claim 1 , wherein the microbial stimu documents cited herein are fully incorporated by reference lation operation comprises introducing an exogenousmicro to the extent such disclosure is not inconsistent with this 55 bial population to the region of interest . invention and for all jurisdictions in which such incorpora - 8 . The method of claim 7 , wherein the exogenous micro tion is permitted . bial population is introduced to the region of interest by When numerical lower limits and numerical upper limits injection of a solution comprising the exogenous microbial are listed herein , ranges from any lower limit to any upper population in the well . limit are contemplated . While the illustrative embodiments 60 9 . The method of claim 1 , wherein the comparison of the of the invention have been described with particularity , it baseline isotopic signature and the induced isotopic signa will be understood that various other modifications will be ture comprises a comparison of the change in the 3CH2D apparent to and can be readily made by those skilled in the concentration . art without departing from the spirit and scope of the 10 . The method of claim 1 , wherein the comparison of the invention . Accordingly , it is not intended that the scope of 65 baseline isotopic signature and the induced isotopic signa the claims appended hereto be limited to the examples and ture comprises a comparison of the change in the 12CH , D , descriptions set forth herein but rather that the claims be concentration . US 10 , 132 , 144 B2 23 24 11 . The method of claim 1 , wherein the multiply substi of interest, wherein the induced isotopic signature tuted isotopologue signature , clumped isotope signature , or comprises multiply substituted isotopologue signa position -specific isotope signature is determined by : tures, clumped isotope signatures, and /or position - spe modeling an expected temperature -concentration depen cific isotope signatures ; dence of the isotopologues for a hydrocarbon species of 5 ( f ) comparing the baseline isotopic signature and the interest; induced isotopic signature to determine whether the measuring the concentration of isotopologues of the type ofhydrocarbons being produced from the well has hydrocarbon species of interest present in the sample ; changed , wherein the type of hydrocarbons being pro comparing the measured concentration of isotopologues with the expected concentration of isotopologues ; and 10 duced from the well comprises thermogenic hydrocar converting the measured concentration of isotopologues bons , biogenic hydrocarbons , and induced biogenic to a storage temperature of the hydrocarbon species of hydrocarbons ; and interest . ( g ) modifying the microbial stimulation operation by at 12 . The method of claim 1 , further comprising developing least one of changing the type of nutrients being a new stimulation strategy based on the type of hydrocar - 15 introduced to the region of interest, changing the vol bons being produced in the well . ume or rate of nutrients being introduced to the region 13 . The method of claim 1, further comprising producing of interest, and changing the community composition hydrocarbons. of the exogenous microbial population being intro 14 . A method of producing hydrocarbons comprising : duced to the region of interest ; wherein the modifying ( a ) obtaining one or more hydrocarbon samples from a 20 is based on the comparison of the baseline isotopic well in a region of interest ; signature and the induced isotopic signature . ( b ) analyzing the one or more samples to determine a 15 . The method of claim 14 , wherein the nutrients com baseline isotopic signature for a hydrocarbon species of prise one or more of molasses , nitrates , vitamins , and interest, wherein the baseline isotopic signature com - surfactants . prises one or more of multiply substituted isotopologue 25 16 . The method of claim 14 , wherein the comparison of signatures, clumped isotope signatures, and position the baseline isotopic signature and the induced isotopic specific isotope signatures ; signature comprises a comparison of the change in the ( c ) performing a microbial stimulation operation on the 13CH . D concentration . region of interest , wherein the microbial stimulation operation comprises at least one of introducing nutri - 30 the 17. The method of claim 14 , wherein the comparison of ents into the region of interest or introducing an exog the baseline isotopic signature and the induced isotopic enous microbial population to the region of interest ; signature comprises a comparison of the change in the ( d ) obtaining one or more post- stimulation hydrocarbon 12CH2D , concentration . samples from the well; 18 . The method of claim 14 , further comprising producing ( e ) analyzing the post- stimulation sample to determine an 35 hydrocar induced isotopic signature for the hydrocarbon species * * * *